NASA finds Goldilocks planet – the right size and place

Kepler habitable planets. Scientists have just found Kepler-62e and Kepler-62f.
AFR

by
Joel Achenbach

Planet-hunting astronomers have revealed they’ve found two tantalising worlds, seemingly congenial to life as we know it, orbiting a star 1200 light years away.

Neither planet has been seen directly and if they actually harbour life is speculative. Their presence has been inferred by the regular dimming of their parent star, as observed by NASA’s Kepler Space Telescope.

Kepler-62f is just a bit larger than Earth and it’s in the so-called Goldilocks position, orbiting the star, Kepler-62, at a distance where water could be splashing freely at the surface. Scientists think Kepler-62f is rocky like Earth.

They also found Kepler-62e, which is closer to the parent star and warmer but also within what is presumed to be a habitable zone. Scientists think the size of Kepler-62e makes it a good candidate for being a water world, completely covered by ocean.

All told, the Kepler team revealed seven new planets in two planetary systems on Thursday, publishing findings online in Science and via a news conference at NASA’s Ames Research Centre .

“This is really cool," said Pete Worden, the director of NASA Ames.

The Kepler telescope was launched in 2009 and has found more than 100 planets. The ultimate goal of planet-hunting astronomers is to find a true Earth twin, a planet that is no larger than our own and in an Earth-like orbit.

Kepler- 62f comes very close. The mass of the planet is unknown but computer models suggest it is rocky and not a gas giant like Jupiter or Saturn or an ice world like Uranus or Neptune.

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“We think that it may have significant land masses," Kepler lead scientist William Borucki said.

The first exoplanet – a planet outside our solar system – was found in 1995, and since then a frenzy of planet-hunting has produced hundreds of discoveries. Extrapolating from what has been observed, astronomers increasingly think that planets are commonplace and that our galaxy alone could have billions of planets in life-friendly orbits.

To date, extraterrestrial life remains conjectural. No life has been found beyond Earth. Even if an Earth twin were found, the superficial resemblance would not mean we’d found a planet that was actually inhabited. As Mr Borucki noted, “We don’t know what life requires to get started."

The Kepler telescope, which circles the sun in an Earth-trailing orbit, looks for stars that dim in a regular pattern, which would suggest that a planet is passing between the star and the telescope. Several such regularly spaced occulations will tell the astronomers they have a real planet dimming that star and not some random fluctuation in starlight. The amount that the star dims will also give the Kepler team a sense of the diameter of the planet. As with other techniques for planet-finding, the big, hot, planets in close-in orbits have been the easiest to detect. Refinement of methods have let astronomers find smaller planets which are farther from their stars– such as Kepler-62e and 62f.